Hey guys I have been helping a friend of mine try too clear the error codes on her 02 A4 1.8L. I got the Following Codes.

P0411 - Secondary Air Injection System Incorrect Flow Detected

I know this one is common But was just wondering if you had any tips on diagnosing it better. Btw this is the First turbo charged car i have worked on so simple details please lol

P0420 - Catalyst System Efficiency Below Threshold (Bank 1)

How do I tell if this is a Bad O2 sensor or a Bad Cat?

P1296 - This one is might be worked out. I replaced the Temp sensor (Since the gauge on her dash was not getting any input either) and cleared this code it has not come back in the 2 days since then so should be ok but any advice on this is welcome.

That's it. Oh one other thing do any of you know a good site where i can pick up cheap Cosmetic parts Like the lugnut covers on the Tires some buttons on the inside and things like that? Also bigger body parts like the Underhang under the front Bumper and Lights for same?

 

Bump No one can help me with this?

 

Check my message, recurring problem.... in the A4 forum. I got many of the same error codes, and it's becoming a big mystery. Cat is my growing belief on my issues.

 

the p1296 is the thermostat.
i changed that and ever since the code its been cleared. and my temperature gauge went to half from 0.. before the thermostat i changed the temp sensor and i was still getting the p1296 code. make sure u buy the thermostat with the whole housing.

 

sound slike an o2 sensor and a vaccume leak.

 

Replace your Aft O2 sensor for the P0420, if that doesn't do the trick, replace the Catalytic converter. For your P0411, your SAI pump should come on when you start the car in the mornings, it stabilizes the idle, if it doesn't is time for a new one.